CN101836869A - The multi-layered impedance matching structure of ultrasound probe - Google Patents

Abstract

A kind of acoustic stack (270) that is used for ultrasound probe (106) comprises piezoelectric layer (272) with top side and bottom side and a plurality of coupling intervals (222,224,226,228,230) that form matching layer structure (220).In the coupling interval (222-230) each comprises spring layer (234,236,238,240,242) that comprises first material and the quality layers (244,246,248,250,252) that comprises second material different with first material.Be arranged near the spring layer (234) of the coupling interval (222) of piezoelectric layer (272) thinner than the spring layer (236-242) of other coupling interval (224-230).

Description

The multi-layered impedance matching structure of ultrasound probe

Technical field

In general, theme disclosed herein relates to ultrasound probe (ultrasound probe), more particularly, relates to the acoustic stack (acoustical stack) in the ultrasound probe.

Background technology

Ultrasound probe have usually many separately with the probe the corresponding acoustic stack of image-forming component.Each acoustic stack has with stack arrangement several layers attached together.Piezoelectric layer in the lamination is formed by the piezoelectric with high impedance, for example piezoelectric ceramics.

Coupling (matching) layer is arranged on the top side of piezoelectric layer, so that have conversion acoustic impedance between low-impedance outside or the lens in piezoelectric layer with high impedance and probe.Low ESR can be based on the acoustic impedance of water to be scanned, human body or other object.Many probes comprise that wherein the about quarter-wave of each matching layer is thick based on two matching layers of quarter-wave coupling.Each quarter-wave matching layer is used for the impedance in the limited broadband of conversion.Use two quarter-wave matching layers that bandwidth range is limited between 80% and 90%.In order in big bandwidth, to realize impedance matching, need the quarter-wave matching layer of larger amt.But the numbers of poles the earth that increases the quarter-wave matching layer increases the thickness of lamination, and increases signal attenuation.In addition, stack material becomes and more and more is difficult to cutting, and may be difficult to still finding the suitable material that is used for each quarter-wave matching layer in control expection geometry and the impedance.

In addition, a plurality of layers that proposed the multiple different materials that uses the gradient or classification (graded) matching layer of the material with continuous variation impedance or have different acoustic impedances replace the quarter-wave matching layer that disperses.But the gross thickness of these classification matching layer configuration requirement matching layers is blocked up.Only when within the scope of thickness at least one or two wavelength of classification matching layer, just realize good matching properties.At this thickness, the overdamp of ultrasonic signal takes place.Cutting operation is very difficult because of the thickness of layer, because cut for being difficult than thick-layer, for thin layer then be not, and demanding blade exposure.But, if the thickness of classification matching layer, then will produce bad coupling or ring in the bandwidth shake (ringing) less than a wavelength.

Summary of the invention

In one embodiment, the acoustic stack that is used for ultrasound probe comprises piezoelectric layer with top side and bottom side and a plurality of coupling intervals (section) that form the matching layer structure.Each coupling interval comprises spring (spring) layer that comprises first material and quality (mass) layer that comprises second material different with first material.Be arranged near the spring layer of the coupling interval of piezoelectric layer thinner than the spring layer of other coupling interval.

In another embodiment, a kind of method of matching layer structure of the acoustic stack that is used to form ultrasound probe, comprise forming the first coupling interval, the described first coupling interval be included in the first coupling interval the bottom side spring layer and in the quality layers of the top side of the first coupling interval.The bottom side of the first coupling interval one of is configured to be attached in piezoelectric layer and the quarter-wave matching layer.Spring layer comprises spring material, and quality layers comprises that impedance is higher than the quality materials of spring material.Form at least one additional coupling interval, described additional coupling interval be included in additional coupling interval the bottom side spring layer and in the quality layers of the top side of additional coupling interval.The bottom side of additional coupling interval is configured to be attached to the top side of the first coupling interval.Spring layer comprises spring material, and quality layers comprises quality materials.

In yet another embodiment, a kind of method of matching layer structure of the acoustic stack that is used to form ultrasound probe comprises: comprise the spring layer of spring material and form the quality layers that comprises quality materials on spring layer by formation, form the first coupling interval.Quality materials has the density that is higher than spring material.By forming alternative with the quality layers that comprises quality materials, as to comprise spring material spring layer, on the first coupling interval, form N coupling interval.

Description of drawings

Fig. 1 illustrates the ultrasonic system that forms according to one embodiment of present invention.

Fig. 2 illustrates the miniaturized ultrasonic wave system system with three-dimensional (3D) ability that forms according to one embodiment of present invention.

Fig. 3 illustrates the mobile ultrasonic imaging system that forms according to one embodiment of present invention.

Fig. 4 illustrates portable or the miniature ultrasonic imaging system that forms according to one embodiment of present invention.

Fig. 5 illustrates the matching layer structure that is used for ultrasound probe that forms according to one embodiment of present invention.

Fig. 6 illustrates according to one embodiment of present invention the lumped-circuit that is used for quarter-wave transmission line (lumped circuit) that forms, and it provides the electrical equivalent of the engineering properties of the used coupling interval of the matching layer structure of design of graphics 5.

Fig. 7-10 illustrates according to one embodiment of present invention, based on the acoustic simulation of the bandwidth performance of the matching layer structure of Fig. 5.

Figure 11 illustrates according to one embodiment of present invention, is used for to determine to be included in the method for quantity of coupling interval of the matching layer structure of probe.

Figure 12 illustrates and comprises according to one embodiment of present invention the matching layer structure that forms and the acoustic stack of quarter-wave matching layer.

The specific embodiment

Foregoing invention content and followingly will be better understood to being described in detail in when reading in conjunction with the accompanying drawings of some embodiment of the present invention.Illustrate at accompanying drawing on the meaning of sketch of functional device of each embodiment, these functional devices are not necessarily indicated the division between the hardware circuit.Therefore, for example, one or more (for example processor or the memorizeies) in these functional devices can be realized in separate piece of hardware (for example, general purpose signal processor or random access memory, hard disk etc.).Similarly, program can be a stand-alone program, can be used as subroutine and merges in the operating system, can be the function in the install software bag, etc.Should be appreciated that each embodiment is not limited to layout shown in the drawings and instrument.

This paper is employed, described and hat has speech " " or " a kind of's " key element or step should be understood that not get rid of the situation of a plurality of described key elements or step with singulative, unless offered some clarification on this eliminating situation.In addition, among the present invention to the existence that is not to be intended to be interpreted as getting rid of other embodiment that combines described feature equally of quoting of " embodiment ".In addition, unless opposite offering some clarification on, the key element of " comprising " or " having " band special properties or the embodiment of a plurality of key elements can comprise this class key element that other does not have the sort of character.

Fig. 1 illustrates the ultrasonic system 100 that comprises emitter 102, and element (for example piezoelectric element) array 104 that emitter 102 drives in the probe 106 is so that be transmitted into the pulse ultrasonic wave signal in the body.Probe 106 can comprise matching layer structure (as Fig. 5 and shown in Figure 12).Element 104 for example can be arranged to one dimension or two dimension.Can use various geometries.System 100 can have the probe port 120 that is used to hold probe 106, perhaps pops one's head in 106 can be hardwired to system 100.

Ultrasonic signal is from the structure of human body, as fatty tissue or muscular tissue back scattering (back-scatter), so that produce the echo that turns back to element 104.Echo is received by receptor 108.The echo that is received is through Beam-former 110, and described Beam-former 110 is carried out wave beam and formed and export radio frequency (RF) signal.Then, the RF signal is through RF processor 112.Alternatively, RF processor 112 can comprise compound demodulator (not shown), and it is right so that form the homophase and quadrature (in-phaseand qudrature:IQ) data of expression echo-signal that described compound demodulator carries out demodulation to the RF signal.Then, RF or IQ signal data can be routed directly to memorizer 114 for storage.

Ultrasonic system 100 also comprises processor module 116, so that handle the ultrasound information that obtains (for example RF signal data or IQ data to), and preparation ultrasound information frame is for the demonstration on display 118.Processor module 116 is fit to obtaining ultrasound information is carried out one or more processing operations according to a plurality of optional ultrasound wave forms (modality).Institute's ultrasound information that obtains can be handled during scan session when receiving echo-signal and show in real time.As a supplement or substitute, ultrasound information can be temporarily stored in during scan session in memorizer 114 or the memorizer 122, processs and displays with off-line operation then.

User interface 124 can be used for to system's 100 input data, adjustment is set and the operation of processor controls module 116.User interface 124 can have keyboard, trace ball and/or mouse and a plurality of knob, switch or for example other input equipment of touch screen.Display 118 comprises to the user and presents the patient information that comprises the diagnostic ultrasound image for diagnosis and one or more monitors of analyzing.The two dimension (2D) of one or two ultrasound data stored in memorizer 114 and the memorizer 122 and/or three-dimensional (3D) data set, this class data set of wherein access (access) is so that present 2D and 3D rendering.Also can obtain and store a plurality of continuous 3D data sets in time, for example so that provide the real-time 3D or the four-dimension (4D) to show.By using user interface 124, can revise image and also manually adjust the display setting of display 118.

Fig. 2 illustrates the miniaturized ultrasonic wave system system 130 with 3D ability, and it has the probe 132 that can comprise the matching layer structure.Probe 132 can be configured to obtain the 3D ultrasound data.For example, probe 132 can have before the 2D array 104 at the probe 106 described element of transducers of Fig. 1.Provide (also can comprise integrated display 136) user interface 134, to receive order from operator.

This paper employed " miniaturization " expression ultrasonic system 130 is hand-held or portable device, perhaps is configured to carry with the little case or the knapsack of staff, pocket, briefcase size.For example, ultrasonic system 130 can be the portable device with about 2.5 inches thick, about 14 inches wide of typical laptop computer sizes-for example have and about 12 inches high sizes.Ultrasonic system 130 can be great about 10 pounds, thereby the easy operating personnel carry.Integrated display 136 (for example internal display) also is provided, and it is configured to show medical image.

Ultrasound data can send to external device (ED) 138 via wired or wireless network 140 (perhaps directly connecting, for example via serial or parallel cable or USB port).In certain embodiments, external device (ED) 138 can be computer or the work station with display.Alternatively, external device (ED) 138 can be to receive view data and can show or the separate outer display or the printer of print image from hand-carried ultrasound wave system system 130, and it can have the resolution higher than integrated display 136.Should be noted that each embodiment can unite in conjunction with the miniaturized ultrasonic wave system with different size, weight and power consumption realizes.

Fig. 3 illustrates the mobile ultrasonic imaging system 144 that is arranged on the mobile base 146.Ultrasonic imaging system 144 can be called the system based on go-cart again.Display 142 and user interface 148 are provided, and should be appreciated that display 142 can be independent of user interface 148 or can separate with it.System 144 has at least one probe port 150, is used to admit the probe (not shown) that can comprise the matching layer structure.

Alternatively, user interface 148 can be a touch screen, thereby allows operator to select option by touching shown figure, icon etc.User interface 148 also comprises control knob 152, and described control knob can be used for providing according to expection or needs and/or according to common institute controls ultrasonic imaging system 144.User interface 148 provides a plurality of interface options, but the described interface options of user's physical operations so that carry out alternately with the ultrasound data that can be shown and other data, and input information and being provided with and the change sweep parameter.Interface options can be used for specific input, input able to programme, text input etc.Keyboard 154 and trace ball 156 for example can be provided.

Fig. 4 illustrates portable or miniature ultrasonic imaging system 170, and wherein display 172 and user interface 174 form individual unit.As example, miniature ultrasonic imaging system 170 can be that about 2 inches wide, about 4 inches long and about 0.5 inch thick and weight are less than 3 ounces.Display 172 can be 320 * 320 pixel color LCD display (can show medical image 176 thereon) for example.Alternatively, the typewriter-like keyboard 180 of button 182 can be included in the user interface 174.The probe 178 and system's 170 interconnection that can comprise the matching layer structure.

Can be according to each self-supporting multi-functional control (control) 184 distribution function of system operation modes.Therefore, each in the multi-functional control 184 can be configured to provide a plurality of different actions.In case of necessity, related with multi-functional control 184 label viewing area 186 can be included on the display 172.System 170 can have additional key and/or the control 188 that is used for specific function, and described specific function can include but not limited to " freezing (freeze) ", " degree of depth control ", " gain control ", " color mode ", " printing " and " storage ".

Matching layer structure as herein described one of can be used for replacing in the acoustic stack of ultrasound probe 106 in quarter-wave matching layer or the classification matching layer at least.The technique effect of at least one embodiment is, can be used for the approximate stepped impedance tapering of realizing by the matching layer structure (taper) based on the mechanical equivalence of lump machinery match circuit (being called lumped-circuit in this article again).The actual realization of lump machinery match circuit uses the combination of the thin-material layers with selected engineering properties to form.Assembly with layer of different engineering propertiess will imitate equivalent mass and spring agitator.

The matching layer structure comprises that at least two are called the matching layer equivalence section of mating interval in this article.Each coupling interval comprises at least two kinds of materials that can form in layer.These two kinds of materials are chosen according to the engineering properties of material.One of for example, in the described material, be called spring material in this article, be than low-loss and low density material, for example such as epoxy resin-matrix negative photoresist (epoxy-based negative potoresist) SU8 ^TMPerhaps polyimide material (polyimide material) Kapton ^TMPolymer or thin film, and can have the acoustic impedance that is lower than 1.5 million Rayleighs (MegaRayl:MR).Another kind of material is called quality materials in this article, is the higher density material, for example tungsten, copper or other metal, and can have more acoustic impedance near 30MR.Should be appreciated that and to use other material.Each coupling interval has much smaller than quarter-wave, the thickness of about 50 microns (μ m) for example, but also expects other thickness.

The coupling interval recently forms by amount or the percentage of adjusting every kind of material in each coupling interval.For example, the coupling interval with high impedance has the highest percentage ratio of quality materials and the lowest percentage of spring material, and the layer with lowest impedance has the lowest percentage of quality materials and the highest percentage ratio of spring material.Coupling interval with high impedance is positioned in lamination near piezoelectric layer, and the coupling interval with lowest impedance be positioned to when when mating than the Low ESR medium near lens.

Fig. 5 illustrates the matching layer structure 220 with 5 equivalent matched intervals.Should be appreciated that the coupling interval that can use other quantity.These coupling intervals can be called the first coupling interval (ML1) 222, the second coupling interval (ML2) 224, the 3rd coupling interval (ML3) 226, the 4th coupling interval (ML4) 228 and the 5th coupling interval (ML5) 230.Matching layer structure 220 has thickness 276, and is included in the acoustic stack 270 that has piezoelectric layer 272 at least.Can on lamination 270, form lens 274.Though not shown, in lamination 270, can comprise extra play, for example separate coupling (dematching) interval, support (backing) piece, as additional matching layer of quarter-wave layer etc.

Among the coupling interval 222-230 each has and comprises the two thickness 232 of quality materials and spring material.In one embodiment, each had same thickness 232 among the coupling interval 222-230.In another embodiment, the thickness 232 of coupling interval 222-230 is variable.Should be noted that the thickness that coupling interval 222-230 only is shown for convenience of explanation, rather than carry out convergent-divergent with respect to the thickness of piezoelectric layer 272 and lens 274.

Among the coupling interval 222-230 each comprises quality layers and spring layer.In certain embodiments, one or more among the coupling interval 222-230 can only comprise quality layers or only comprise spring layer.The material layer that term " spring layer " expression has thickness and specified impedance, it makes layer mechanical impedance effect mainly just as spring when being attached to quality layers.The material layer that term " quality layers " expression has thickness and specified impedance, it makes layer mechanical impedance effect just as quality when being attached to spring layer.The first coupling interval 222 comprises spring layer 234 and quality layers 244.The second coupling interval 224 comprises spring layer 236 and quality layers 246.The 3rd coupling interval 226 comprises spring layer 238 and quality layers 248.The 4th coupling interval 228 comprises spring layer 240 and quality layers 250.The 5th coupling interval 230 comprises spring layer 242 and quality layers 252.Among spring layer 234-242 and the quality layers 244-252 each has thickness (back is further discussed), but in certain embodiments, the thickness of each can be according to the manufacturing process slight modification at coupling interval 222-230 in spring layer and the quality layers.

Can change among the coupling interval 222-230 each the quality materials and the ratio or the percentage ratio of spring material, so that realize the expection variation of acoustic impedance along transmission line.For example adopt conducting resinl, binding agent or other material that the bottom side 278 of the first coupling interval 222 is attached to piezoelectric layer 272.In order to mate the acoustic impedance of piezoelectric layer 272, the first coupling interval 222 has among the coupling interval 222-230 the high impedance of any.In order to realize high impedance, 222-230 compares with other coupling interval, and the first coupling interval 222 has the largest percentage or the ratio of quality materials.Therefore, in general, for real material, the thickness 254 of quality layers 244 is greater than the thickness of the quality layers 246-252 of any among other coupling interval 224-230, and in general, for real material, when being lower than the medium coupling of for example water of piezoelectric layer 272 or lens 274 with impedance, the thickness 256 of spring layer 234 mates the thin thickness of the spring layer 236-242 of any among interval 224-230 than other.

The bottom side 280 of the second coupling interval 224 is attached to the top side 282 of the first coupling interval 222.The acoustic impedance of the second coupling interval 224 is less than the impedance of the first coupling interval 222.In order to realize lower acoustic impedance, will add in the second coupling interval 224 than still less quality materials in the first coupling interval 222.Therefore, the thickness 254 of the thickness 258 specific mass layers 244 of quality layers 246 is thin.In addition, the thickness 260 of spring layer 236 is greater than the thickness 256 of spring layer 234.Repeat this pattern in whole matching layer structure 220, so that the 5th coupling interval 230 has among the coupling interval 222-230 the minimum acoustic impedance of any.In order to realize minimum acoustic impedance, other coupling interval 222-230 compares with all, and minimum quality materials is added the 5th coupling interval 230.Therefore, the thickness 262 of quality layers 252 is than any is thin among other quality layers 244-250, and the thickness 264 of spring layer 242 is than any is thick among other spring layer 234-240.In other words, spring layer 234-242 can have the thickness that increases continuously when the distance of distance piezoelectric layer 272 increases, and quality layers 244-252 can have the thickness of continuous reduction when the distance of distance piezoelectric layer 272 increases.In another embodiment, the variation of thickness can be discontinuous, that is to say that one or more spring layer 234-242 can have the identical thickness with another spring layer 234-242, and one or more quality layers 244-252 can have the identical thickness with another quality layers 244-252.In yet another embodiment, the thickness one of in quality layers or the spring layer can keep constant, reduces or increase the thickness of another layer simultaneously.

Fig. 6 illustrates the lumped-circuit 200 that is used for quarter-wave transmission line, and it provides the electrical equivalent of the engineering properties of the used coupling interval 222-230 of the matching layer structure 220 of design of graphics 5.In other words, the electric assembly in the lumped-circuit 200 (for example inducer, capacitor etc.) can be used for estimating the acoustic properties of spring layer material and quality layers material.Therefore, lumped-circuit 200 illustrates the related of spring layer 234-242 and quality layers 244-252.In this example, lumped-circuit 200 is corresponding to one in the matching layer structure 220 coupling interval 222-230.Among the coupling interval 222-230 each is by 200 expressions of independent lumped-circuit.Lumped-circuit 200 has 202,204,206 and two capacitors 208,210 of three inducers.In another embodiment, under the simple form of circuit 200, can use single inductor and single capacitor; And in other embodiments, can use the inducer and the capacitor of varying number.Spring layer 234-242 capacitors available 208 and 210 electric capacity characterize, and the inductance of quality layers 244-252 available inductors 202-206 characterizes.

Three quality layers of example modelled shown in Figure 6 (inducer) and two spring layers (capacitor), so that imitation quarter-wave layer function, but should be appreciated that this function can realize according to expecting that at least relative bandwidth disposes with other.In aforesaid easy configuration, can use single inductor and single capacitor.Fig. 6 can be used for illustrating the physics understanding to the structure of coupling interval.General solution also can be analyzed by classical LC ladder type (ladder) filter theory.

The electrical equivalent of the engineering properties that makes up used quality layers of coupling interval 222-230 and spring layer is provided in equation 1 and equation 2.

$\mathrm{LS}:=\frac{\mathrm{ZL}\·4}{\mathrm{\ωr}\·{\mathrm{\π}}^2}---\left(1\right)$

$\mathrm{CP}:=\frac{1}{\mathrm{ZL}\·\mathrm{\ωr}\·\sqrt{2}}---\left(2\right)$

Therefore, the value of the inductance (LS) of lumped-circuit 200 examples and electric capacity (CP) is based on the resonance frequency omega r of the line impedance (ZL) (for example acoustic impedance) of coupling interval 222-230 and 106 the mid frequency of popping one's head in.The quarter-wave effect by (LS+CP) with (2 * LS+CP) unitary serial is related realizes.ZL can be selected or predetermined impedance value or according to further described calculating hereinafter.

The combination of the electrical equivalent of quality layers and spring layer provides the characteristic to modeling one of among the coupling interval 222-230.To mating each among the interval 222-230, repeat equation 1 and equation 2 to calculate LS and CP, each of wherein mating among the interval 222-230 has different ZL.As previously described, ZL is along with reducing in respectively the mating interval 222-230 of the direction of leaving piezoelectric layer 272.Therefore, has at least two circuit 200 cascade mutually of suitable assembly, so that realize the big bandwidth match around the resonance frequency omega r.Each mates the LS of interval 222-230 and the electrical analogue that the CP value can be used for and be called the acoustic stack of advising 270 of Mason model, thereby allows electric device and acoustic construction coupling.

Fig. 7-10 illustrates the acoustic simulation based on the bandwidth performance of matching layer structure 220 in the lamination 270.When calculating simulation, the thickness 276 of coupling interval 222-230 can that is to say based on the classical Mason model that does not have material character to optimize, and does not consider diffraction law and lens decay among the coupling interval 222-230.Acoustic simulation 300,302,330 and 332 can use the inductance and the capacitance that calculate with equation 1 and equation 2 respectively to calculate.

Popped one's head in 106 o'clock in design, can simulate laminated construction, so that can discern the coupling interval 222-230 that satisfies the required minimum number of probe standard.Less coupling interval brings littler thickness 276, and this improves decay.Can an appointed parameter be-6 decibels (dB) and-the expection bandwidth of 20dB.Also can consider other parameter.

Fig. 7 and Fig. 8 illustrate the acoustic simulation 300 and 302 of the probe transfer function of being calculated according to the probe 106 that is associated with matching layer structure 220 in lamination 270 respectively.Among Fig. 7, use 10 coupling interval 222-230 of gross thickness 276 with 500 μ m.Among Fig. 8, use 5 coupling interval 222-230 of gross thickness 276 with 250 μ m.Simulation is based on 3 megahertzes (MHz) mid frequency array.

Fig. 7 illustrates simple or unidirectional transmission line 304 and reversible line 306.Fig. 8 illustrates unidirectional transmission line 316 and reversible line 318.Reversible line 306 and 318 shows because of ultrasonic signal propagates reducing of the bandwidth that causes by lamination 270 twice (for example transmitting and receiving signal).In other words, when considering to transmit and receive signal, overall decay is bigger.Owing to there are more coupling intervals among Fig. 7,, circuit 304 and 306 on bandwidth, has bigger ripple so comparing with 318 with circuit 316.In one embodiment, can reduce the ripple amplitude by for example using ladder-type filter composition algorithm fine setting layer character.Bandwidth can for example compare between the reversible line 306 and 318, whether provides estimated performance so that determine the matching layer structure with 5 coupling intervals.Additional simulation can be used and be less than 5 coupling intervals or carry out at 5 and 10 any amount of coupling intervals that mate between the interval.In addition, also expection has the matching layer structure 220 of mating intervals more than 10.In certain embodiments, can simulate so that discern the minimum number of the coupling interval 222-230 that will satisfy the probe standard.

Similarly, Fig. 9 and Figure 10 illustrate the acoustic simulation 330 and 332 of the probe transfer function of being calculated according to the probe 106 that is associated with matching layer structure 220 in lamination 270 respectively. Simulation 330 and 332 is based on 8MHz mid frequency array.Among Fig. 9, use 10 coupling interval 222-230 of gross thickness 276 with 500 μ m.Among Figure 10, use 5 coupling interval 222-230 of gross thickness 276 with 250 μ m.

Fig. 9 illustrates unidirectional transmission line 334 and reversible line 336.Figure 10 illustrates unidirectional transmission line 346 and reversible line 348.Can compare two bandwidth performances between the simulation 330 and 332 once more, so that the minimum number of the coupling interval 222-230 of probe standard is satisfied in identification.

By will be as the heavy material (quality) in the double-decker of the equivalence of single quarter-wave matching layer one of (for example mate among the interval 222-230) and elastomeric material (spring) related, realization converts linear electrical parameter to engineering properties, i.e. quality-spring oscillation mode rather than as the pure electric transmission line parameter such as inductance and electric capacity in equation 1 and the equation 2.Relation in double-deck target acoustic impedance ZL and this two layers between every layer the effective mechanical thickness uses equation 3 and equation 4 to determine.

$\mathrm{Tmass}\left(n\right):=\frac{\mathrm{\&lambda;<figure-callout\; id="2"\; label="m"\; filenames="HSA00000068232900041.png,HSA00000068232900051.png"\; state="\{\{state\}\}">m</figure-callout>}}{2\&CenterDot;\mathrm{\&pi;}}\&CenterDot;\frac{\mathrm{ZL}\&CenterDot;(1-\frac{{\mathrm{<figure-callout\; id="2"\; label="zs"\; filenames="HSA00000068232900041.png,HSA00000068232900051.png"\; state="\{\{state\}\}">zs</figure-callout>}}^2}{{\mathrm{ZL}}^2})}{\mathrm{zm}}---\left(3\right)$

$\mathrm{Tspring}\left(n\right):=\frac{\mathrm{\&lambda;s}}{2\&CenterDot;\mathrm{\&pi;}}\&CenterDot;\frac{\mathrm{zs}}{\mathrm{ZL}}---\left(4\right)$

Equation 3 provides the quality layers thickness (Tmass) as the function of the acoustic impedance (zs) of the acoustic impedance (zm) of the wavelength (λ m) of matching layer impedance (ZL), heavy type or quality (m) material character and spring (s) material character-be quality materials, quality materials and spring material.Equation 4 provides as matching layer impedance (ZL) and spring (s) material character, is the spring layer thickness (Tspring) of function of the acoustic impedance (zs) of the wavelength (λ s) of spring material and spring material.By changing the matching layer impedance, equation (3) and equation 4 can be used for describing each among the coupling interval 222-230.

Figure 11 illustrates a kind of definite method that will be included in the quantity of the coupling interval 222-230 in the probe 106 matching layer structures 220 that is used for.370, determine geometry and the target or the estimated performance of probe 106.For example, select mid frequency.But the percentage ratio of nominated bandwidth also in addition, for example bandwidth-6db and-20db in each percentage ratio.

372, select to be used for the material of spring layer 234-242 and quality layers 244-252.For example, can select SU8TM to be used for spring material, and can select tungsten to be used for quality materials.Can use other material.In one embodiment, identical spring material can be used for all spring layer 234-242, and identical quality materials can be used for all quality layers 244-252.In another embodiment, different spring material and/or quality materials can be used for one or more among layer 234-252.

374, determine to treat the quantity of mimic coupling interval 222-230.As previously described, the probe performance can use the coupling interval 222-230 of varying number to simulate, so that definite coupling interval 222-230 that the minimum number of estimated performance will be provided.Alternatively, can select the coupling interval 222-230 of predetermined quantity, for example 3,5 or 10 coupling interval 222-230.In another embodiment, can select 2 or 3 the coupling interval 222-230 that mate interval 222-230 as minimum number to be considered.

376, can determine to mate among the interval 222-230 acoustic impedance of each.In one embodiment, the acoustic impedance of each can be based on successively decrease acoustic impedance or acoustic impedance is reduced to any other curve of the low acoustic impedance (it can be 1.5 million Rayleighs in one embodiment) of lens from the acoustic impedance (it can be 30,000,000 Rayleighs in one embodiment) of piezoelectric layer of exponential decrease acoustic impedance, rule among the coupling interval 222-230.In another embodiment, for separating matching technique, the target acoustic impedance of coupling interval 222-230 can use following formula 5 and 6 to determine:

$\mathrm{ZRCKSym}(N,k):={[{[\mathrm{ZC}\&CenterDot;{(1-{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="HSA00000068232900041.png,HSA00000068232900051.png"\; state="\{\{state\}\}">k</figure-callout>}}^2+\frac{8}{{\mathrm{\&pi;}}^2}\&CenterDot;k^2)}^2\&CenterDot;\mathrm{\&omega;r}\left(k\right)]}^{2\&CenterDot;N}\&CenterDot;\mathrm{ZR}]}^{\frac{1}{2\&CenterDot;N+1}}---\left(5\right)$

$\mathrm{ZmL}\_(N,n,k):={\left(\frac{\mathrm{ZRCKSym}(N,k)}{\mathrm{ZR}}\right)}^{\frac{2\&CenterDot;(N-n)+1}{2\&CenterDot;N}}\&CenterDot;\mathrm{ZR}---\left(6\right)$

Wherein, ZC is the acoustic impedance of piezoelectric layer 272, ZR is the acoustic impedance of radiation medium, ω r (k) is the resonant frequency (pulsation) relevant with piezoelectric coupling coefficient, and k is the coefficient of coup, and N is the quantity of coupling interval, n be to n coupling interval from the enumerator of piezoelectric layer 272 to lens 274 counting, and ZmL (N, n, k) be n the coupling interval acoustic impedance.Therefore, the acoustic impedance of coupling interval 222-230 can based in the acoustic impedance of the resonant frequency (ω r) of probe 106, the acoustic impedance of piezoelectric layer 272 (the perhaps acoustic impedance of quarter-wave matching layer (if use)) and lens 274 one of at least.Should be appreciated that for other technology the acoustic impedance of coupling interval 222-230 can use different equatioies to determine.In another embodiment, can select different materials to be used for mating the one or more of interval 222-230.For example, can select to have more low-impedance spring material and be used for layer, and the different spring materials that can select to have higher resistance are used for the coupling interval of the most close piezoelectric layer 272 near lens 274.

In one embodiment, 378, the thickness of each can be according to acoustic impedance, for example definite with equation 3 and equation 4 among each interior quality layers 244-252 and the spring layer 234-242 among the coupling interval 222-230.Therefore, can determine whether the gross thickness 276 of matching layer structure 220 can be accepted, thereby produce admissible signal attenuation.In addition, quality layers 244-252 and spring layer 234-242 as below form in the manufacture process of further argumentation, and in certain embodiments, may exist based on material character and be used within some tolerance, forming the restriction of the manufacturing capacity of some material layer.

380, for example by using the electric capacity and the inductance that calculate with equation 1 and equation 2 to calculate acoustic impedance, to generate the chart of Fig. 7-10.382, determine whether acoustic impedance can be accepted.In addition, can determine whether the thickness of quality layers 244-252 and spring layer 234-242 and the gross thickness 276 of matching layer structure 220 can be accepted.In one embodiment, if bandwidth performance is unacceptable, then this method can turn back to 374, so that specify the coupling interval 222-230 of bigger quantity.In another embodiment, if bandwidth performance can be accepted, then this method can turn back to 374 to specify the coupling interval 222-230 of smaller amounts, so that determine whether to discern the thinnest matching layer structure 220.For example, wish to have minimum number the matching layer structure and thereby have minimum signal attenuation (for example propagation loss) amount, still satisfy the performance of probe 106 simultaneously.In addition, coupling interval 222-230 still less can be easier to make and produce lower cost.In certain embodiments, the method for Figure 11 can be done repeatedly, thereby the coupling interval 222-230 of selection varying number is with definite coupling interval 222-230 that will realize the minimum number of target capabilities.In yet another embodiment, if for example performance is unacceptable or matching layer structure 220 may be difficult to realize according to available manufacturing technology, then this method can turn back to 372, so that select to be used for quality layers 244-252 and the one or more different materials of spring layer 234-242.

In another embodiment, can form the lamination that comprises the quarter-wave matching layer.Figure 12 illustrates the acoustic stack 400 that comprises matching layer structure 402 and quarter-wave matching layer 404.The bottom side 406 of quarter-wave matching layer 404 is attached to the top side 408 of piezoelectric layer 410, and matching layer structure 402 is attached to the top side 412 of quarter-wave matching layer 404.

In one embodiment, quarter-wave matching layer 404 can be included in the lamination 400, so that additional flexibility is provided when selecting spring material.For example, can select to have more low-impedance spring material, thereby allow the better impedance of the coupling interval of the most close lens 414 in the matching layer structure 402.

In another embodiment, quarter-wave matching layer 404 can be between matching layer structure 402 and lens 414.

There are some methods that form quality layers 244-252 and spring layer 234-242 in matching layer structure 220 and 402 that are used in.A kind of method therefor is based on microelectric technique and wafer-process.Spring material can be a photoresist, and described photoresist is through special handling, for example carry out extra filling (loading), the density/speed character that requires with the acoustic impedance with suitable spring material.Quality materials can be the metal with density/speed character that the acoustic impedance of suitable quality materials requires.Quality materials can be any closeer and hard material, such as but not limited to tungsten.Quality materials and spring material all need to make compatible with the variable thickness interlayer.

In one embodiment, photoresist or polymer, as SU8 ^TMCan be used as spring material, and can use the microelectronics photolithography to form pattern.For example, but spin coating SUI ^TMLayer is to form expection thickness.In another embodiment, in order to reduce density of material, can be in coupling interval 222-230 more realize dot matrix pattern (dotpattern), so that reach expection density near on lens 274 one or more.In yet another embodiment, but vacuum moulding machine forms the metal of quality layers.

Matching layer structure 220 can be separated formation with other layer of lamination 270.In one embodiment, silicon dioxide (SiO2) layer can be deposited on the Silicon Wafer that is used to make up matching layer structure 220.During sheltering of carrying out in order to make up matching layer structure 220 and etching operation, can form the hole of passing or running through matching layer structure 220.When forming all quality layers 244-252 and spring layer 234-242, the SiO2 etching solution can be fed to the SiO2 layer by described hole.The complete etching of SiO2 layer will make matching layer structure 220 break away from Silicon Wafer.

In another embodiment, matching layer structure 220 can form by stacked (lamination).Therefore, spring layer 234-242 can use ready-formed for example Kapton ^TMMaterial the layer form, and quality layers 244-252 can use ready-formed for example copper metal material the layer form.The different-thickness of spring layer 234-242 and quality layers 244-252 can be used for forming different coupling interval 222-230, so that realize the expection acoustic impedance.Metal material layer (for example quality layers 244) can be layered on the spring material layer (for example spring layer 234), so that form the first coupling interval 222.The second spring material layer (for example spring layer 236) can be layered on the metal material layer (for example quality layers 244), and second metal material layer (for example quality layers 246) can be layered on the second spring material layer (for example spring layer 236), and the rest may be inferred.

In yet another embodiment, matching layer structure 220 can use digital little printing to form, and digital little printing is the sedimentary technology of a kind of permission material.

Everybody is appreciated that above description is an illustrative rather than restrictive.For example, the foregoing description (and/or its aspect) use that can mutually combine.In addition, can under the situation that does not break away from its scope, carry out multiple modification to adapt to concrete condition or material to theory of the present invention.Though the size of material described herein and type are intended to define parameter of the present invention, they are restrictive anything but, and are example embodiment.By reading above description, many other embodiment it will be apparent to those skilled in the art that.Therefore, scope of the present invention should be determined together with the whole equivalent scope that license to this class claim with reference to the claim of enclosing.In the claims of enclosing, term " comprises " and " wherein " " comprises " and the general English equivalence of " therein " as corresponding term.In addition, in the claims of enclosing, term " first ", " second " and " the 3rd " etc. are only with marking, rather than are intended to apply digital requirement to its object.In addition, the restriction of claims of enclosing not is to write according to the means-plus-function form, and be not to be intended to explain according to 35U.S.C. § 112 the 6th joint, unless this class claim be limited in clearly use before the function statement that does not have other structure word " be used for ... parts ".

This written description uses the example comprise optimal mode to come open the present invention, and makes those skilled in the art can implement the present invention, comprises making and using any device or system and carry out any institute associated methods.Claim of the present invention is defined by claims, and can comprise other example that those skilled in the art expect.If other example of this class has the structural element of the word language that is not different from claims, if perhaps they comprise the equivalent structure key element that has with the non-essence difference of the word language of claims, then they are intended to fall within the scope of claims.

Parts list

Ultrasonic system 100

Transmitter 102

Element 104

Probe 106

Receiver 108

Beam-former 110

RF processor 112

Memory 114

Processor module 116

Display 118

Probe port 120

Memorizer 122

User interface 124

Miniaturized ultrasonic wave system system 130

Probe 132

User interface 134

Integrated display 136

External device (ED) 138

Network 140

Display 142

Mobile ultrasonic imaging system 144

Mobile base 146

User interface 148

Probe port 150

Control knob 152

Keyboard 154

Trace ball 156

Miniature ultrasonic imaging system 170

Display 172

User interface 174

Medical image 176

Probe 178

Keyboard 180

Button 182

Multi-functional control 184

Label viewing area 186

Control 188

Lumped-circuit 200

Inducer 202

Inducer 204

Inducer 206

Capacitor 208

Capacitor 210

Matching layer structure 220

The first coupling interval 222

The second coupling interval 224

The 3rd coupling interval 226

The 4th coupling interval 228

The 5th coupling interval 230

Thickness 232

Spring layer 234

Spring layer 236

Spring layer 238

Spring layer 240

Spring layer 242

Quality layers 244

Quality layers 246

Quality layers 248

Quality layers 250

Quality layers 252

Thickness 254

Thickness 256

Thickness 258

Thickness 260

Thickness 262

Thickness 264

Acoustic stack 270

Piezoelectric layer 272

Lens 274

Thickness 276

Bottom side 278

Bottom side 280

Top side 282

Acoustic simulation 300

Acoustic simulation 302

Unidirectional transmission line 304

Reversible line 306

Unidirectional transmission line 316

Reversible line 318

Acoustic simulation 330

Acoustic simulation 332

Unidirectional transmission line 334

Reversible line 336

Unidirectional transmission line 346

Reversible line 348

The geometry and the performance 370 of definition probe

Select spring material and quality materials 372

Determine the quantity 374 of coupling interval

Determine respectively to mate the acoustic impedance 376 of interval

Determine the thickness 378 of quality layers and spring layer

Calculate acoustical behavior 380

Can performance be accepted? 382

Acoustic stack 400

Matching layer structure 402

Quarter-wave matching layer 404

Bottom side 406

Top side 408

Piezoelectric layer 410

Top side 412

Lens 414

Claims (10)

1. acoustic stack (270) that is used for ultrasound probe (106) comprising:

Piezoelectric layer (272) with top side and bottom side; And

Form a plurality of coupling intervals (222,224,226,228,230) of matching layer structure (220), each the coupling interval in the described coupling interval (222-230) comprises:

The spring layer (234,236,238,240,242) that comprises first material; And

The quality layers (244,246,248 that comprises second material different with described first material, 250,252), wherein, the spring layer (234) that is arranged in the coupling interval (222) of the most approaching described piezoelectric layer (272) approaches than the spring layer (236-242) that other mates interval (224-230).

2. acoustic stack as claimed in claim 1 (270), wherein, the described coupling interval (222) that is positioned at the most approaching described piezoelectric layer (272) comprises than the acoustic impedance from acoustic resistance Chinese People's Anti-Japanese Military and Political College of described piezoelectric layer (272) coupling interval (230) farthest.

3. acoustic stack as claimed in claim 1 (270), wherein, described first material has than the low density of described second material.

4. acoustic stack as claimed in claim 1 (270), also comprise: quarter-wave coupling interval (404) is arranged between described piezoelectric layer (272) and the described matching layer structure (220) and one of between described matching layer structure (220) and the lens (274).

5. acoustic stack as claimed in claim 1 (270), wherein, thickness (256) at spring layer (234-242) described in the described coupling interval (222-230) increases with the distance of described coupling interval (222-230) with described piezoelectric layer (272), and reduces with the distance increase of described coupling interval (222-230) with described piezoelectric layer (272) at the thickness (254) of quality layers (244-252) described in the described coupling interval (222-230).

6. the method for the matching layer structure (220) of an acoustic stack (270) that is used to form ultrasound probe (106), described method comprises:

Form the first coupling interval (222), the described first coupling interval (222) be included in the described first coupling interval (222) bottom side (278) spring layer (234) and in the quality layers (244) of top side (282) of the described first coupling interval (222), the described bottom side (278) of the described first coupling interval (222) one of is configured to be attached in piezoelectric layer (272) and the quarter-wave matching layer (404), described spring layer (234) comprises spring material, and described quality layers (244) comprises that impedance is higher than the quality materials of described spring material; And

Form at least one additional coupling interval (224), described additional coupling interval (224) be included in described additional coupling interval (224) bottom side (280) spring layer (236) and in the quality layers (246) of the top side of described additional coupling interval (224), the described bottom side (280) of described additional coupling interval (224) is configured to be attached to the described top side (282) of the described first coupling interval (222), described spring layer (236) comprises described spring material, and described quality layers (246) comprises described quality materials.

7. method as claimed in claim 6 also comprises:

Determine the acoustic impedance of (376) described first coupling interval (222) and described additional coupling interval (224); And

According at least one material character of described acoustic impedance and described quality materials and the material character of described spring material, determine the thickness (254,258) of (378) described quality layers (244,246).

8. method as claimed in claim 6 also comprises:

Determine the acoustic impedance of (376) described first coupling interval (222) and described additional coupling interval (224); And

According at least one material character of described acoustic impedance and described spring material, determine the thickness (256,260) of (378) described spring layer (234,236).

9. method as claimed in claim 6, wherein said spring material has related acoustic impedance, and wherein said quality materials has related acoustic impedance and material-wavelength, described method comprises that also the acoustic impedance of the acoustic impedance of the material-wavelength according to described quality materials, described quality materials and described spring material determines the thickness of (378) described quality layers (244,246).

10. method as claimed in claim 6, wherein, described spring material has related acoustic impedance and material-wavelength, and described method also comprises according to the acoustic impedance of the material-wavelength of described spring material and described spring material determines (378) described spring layer (234,236) thickness (256,260).

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